The entry of alanine into the gluconeogenic pathway and the regulation of the direction of metabolite flow by enzyme activity will be studied under experimental conditions which may be applicable to human and domestic animal metabolism. Experiments will be carried out with a number of animal species including swine, which may be the best model for man. This will be accomplished by a study of the varied distribution patterns of the alanine aminotransferase and phosphoenolpyruvate carboxykinase isoenzymes in the gluconeogenic tissues from a number of species. Glucose production from alanine in a variety of tissue preparations, including hepatocytes, will be correlated with the level of mitochondrial alanine aminotransferase in order to show its participation in the alanine entry pathway. Isolated mitochondria will be used to study the conversion of alanine to dicarboxylic acids. This investigation will also include a study of the correlation of cytosolic alanine aminotransferase and phosphoenolpyruvate carboxykinase activities, how they are regulated, and how they contribute to the direction of metabolic flux.